| Journey into the Cell | ||||||||||||
| The Endoplasmic Reticulum | ||||||||||||
 What is the endoplasmic reticulum?
The endoplasmic reticulum is an extensive network of membranes composed of both regions with ribosomes and regions without ribosomes. 
Endoplasmic Reticulum, Image courtesy of The Virtual Cell. What are their distinguishing characteristics?
There are two regions of the ER that differ in both structure and function. One region is called rough ER because it has ribosomes attached to the cytoplasmic side of the membrane. The other region is called smooth ER because it lacks attached ribosomes. Typically, the smooth ER is a tubule network and the rough ER is a series of flattened sacs. The rough ER manufactures membranes and secretory proteins. In leukocytes (leuk-) the rough ER produces antibodies (anti-). In pancreatic cells the rough ER produces insulin. The rough and smooth ER are usually interconnected and the proteins and membranes made by the rough ER move into the smooth ER to be transferred to other locations. 
Rough Endoplasmic Reticulum, Copyright Dennis Kunkel. The smooth ER has a wide range of functions including carbohydrate and lipid synthesis. It serves as a transitional area for vesicles that transport ER products to various destinations. In liver cells the smooth ER produces enzymes that help to detoxify certain compounds. In muscles the smooth ER assists in the contraction of muscle cells and in brain cells it synthesizes male and female hormones. 
Smooth Endoplasmic Reticulum, Image courtesy of The Virtual Cell. The space inside of the ER is called the lumen. The ER is very extensive and is continuous with the nuclear envelope. Since the ER is connected with the nuclear envelope, the lumen of the ER and the space inside the nuclear envelope are part of the same compartment. Share your opinions
What do you think about the endoplasmic reticulum? What are the advantages to having an endoplasmic reticulum? Are there any disadvantages? Come on over to the Biology Forum and share your thoughts, opinions and feelings. Until next time... [ Journey into the Cell > The Nucleus > Ribosomes > Mitochondria > Endoplasmic Reticulum > Golgi Complex > Lysosomes > Peroxisomes > Cytoskeleton > Cilia and Flagella ] Previous Features | ||||||||||||
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